To 0.12 g of 1-[6-(1,2,3,6-tetrahydro-pyridin-4-yl)-quinolin-4-yl]-3-(6-trifluoromethyl-pyridin-2-yl)-urea (0.290 mmol) were added subsequently 2 ml of methanol, 0.366 ml of formaldehyde (4.64 mmol) and a solution of 0.055 g of sodium borohydride (1.451 mmol) in 0.8 ml of water. The reaction was slightly exotherm. A small amount of 2M HCl was added to the reaction mixture up to a pH of 3 to destroy the excess of sodium bororhydride. After neutralization with sodium bicarbonate, methanol was evaporated under reduced pressure, water added to the residue, the reaction mixture extracted three times with ethylacetate, the organic phases combined and dried over sodium sulfate and the solvent evaporated under reduced pressure. 120 mg of the desired product were obtained as an off white powder (yield: 97%).
